Rotation Active Sensors Based on Ultrafast Fibre Lasers

Bidirectional mode-locked erbium-doped fiber laser based on an all-fiber gold nanofilm saturable absorber

We demonstrate a bidirectional mode-locked erbium-doped fiber laser by incorporating gold nanofilm as a saturable absorber (SA). The gold nanofilm SA has the advantages of high stability and high optical damage threshold. Besides, the SA exhibits a large modulation depth of 26% and a low saturation intensity of 1.22 MW/cm2 at 1.56 μm wavelength band, facilitating the mode-locking of bidirectional propagating solitons within a single laser cavity. Bidirectional mode-locked solitons are achieved, with the clockwise pulse centered at 1568.35 nm and the counter-clockwise one at 1568.6 nm, resulting in a slight repetition rate difference of 19 Hz. Moreover, numerical simulations are performed to reveal the counter-propagating dynamics of the two solitons, showing good agreement with the experimental results. The asymmetric cavity configuration gives rise to distinct buildup and evolution dynamics of the two counter-propagating pulses. These findings highlight the advantage of the gold nanofilm SA in constructing bidirectional mode-locked fiber lasers and provide insights for understanding the bidirectional pulse propagation dynamics.

A Quantum Ring Laser Gyroscope Based on Coherence de Broglie Waves

In sensors, the highest precision in measurements is given by vacuum fluctuations of quantum mechanics, resulting in a shot noise limit. In a Mach-Zenhder interferometer (MZI), the intensity measurement is correlated with the phase, and thus, the precision measurement (Δn) is coupled with the phase resolution (Δφ) by the Heisenberg uncertainty principle. Quantum metrology offers a different solution to this precision measurement using nonclassical light such as squeezed light or higher-order entangled-photon pairs, resulting in a smaller Δφ and sub-shot noise limit. Here, we propose another method for the high precision measurement overcoming the diffraction limit in classical physics, where the smaller Δφ is achieved by phase quantization in a coupled interferometric system of coherence de Broglie waves. For a potential application of the proposed method, a quantum ring laser gyroscope is presented as a quantum version of the conventional ring laser gyroscope used for inertial navigation and geodesy.

Angular velocity measurement with wide range based on dual-comb Sagnac interferometer

Interferometric fiber optic gyroscopes are widely used in spacecraft, navigation, and autopilot and missile systems due to their high accuracy and fast speed. However, the dynamic measurement range is generally limited to a small value. In this paper, an angular velocity measurement system based on a dual-comb Sagnac interferometer is proposed. The theoretical dynamic range can reach the order of 10⁸ deg/s, which is remarkably superior to that of the conventional fiber optic gyroscopes. To the best of our knowledge, this is the first demonstration of a dual-comb-based passive fiber optic gyroscope system, offering an attractive tool for measuring angular velocity with large dynamic range.